It is proposed to investigate the determinants of differential black fertility by developing dual simultaneous equation models of fertility determination for black and white families from data provided by the National Longitudinal Study. The dependent variable (family size) will be related to a series of economic demographic and sociological explanatory variables. A key objective will be the estimation of the direct and indirect impacts of policy variables such as education by type, non-wage income, availability and cost of child care, labor market conditions, etc. which will aid in the formation of rational population policy. The estimated model will consist of three equations--a fertility equation, a labor supply equation and a labor demand equation--which will be estimated from the NLS data using two- stage least squares. Impact multipliers will be computed for the exogenous policy variables as a guide to policy markers. It is hoped that this research will enhance our understanding of what constitutes the true direct and opportunity costs of fertility and the relevant income variable affecting fertility as well as our understanding of the response timing of fertility decisions.